A wave of frequency 400 Hz propagates in a medium with a velocity of $2000 \mathrm{~m} / \mathrm{s}$

Question

A wave of frequency 400 Hz propagates in a medium with a velocity of $2000 \mathrm{~m} / \mathrm{s}$. The phase difference between the points 12.5 m apart on a straight line coinciding with direction of the wave will be\

Professor PC Thomas Classes · Answer

$\lambda=\frac{\mathrm{v}}{\mathrm{n}}=\frac{2000}{400}=5 \mathrm{~m} / \mathrm{s}$\ $\phi=\frac{2 \pi}{\lambda} \mathrm{x}=\frac{2 \pi}{5} 	imes 12.5=5 \pi$\ Subtract $2 \pi$ from $5 \pi$. Then we get $3 \pi$. Again subtract $2 \pi$ from $3 \pi$. Then we get $\pi$. It is the answer. Remember the answer on phase difference must be less than $2 \pi$ because when the phase difference is $2 \pi$, they are in phase.\